/**
 * Copyright (c) 2011-2023, James Zhan 詹波 (jfinal@126.com).
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.jfinal.template.expr.ast;

import java.lang.reflect.Array;
import com.jfinal.kit.StrKit;

/**
 * FieldGetters 封装官方默认 FieldGetter 实现
 */
public class FieldGetters {

    /**
     * NullFieldGetter
     *
     * 用于消除 FieldKit.getFieldGetter(...) 中的 instanceof 判断，并且让 Map fieldGetterCache
     * 中的 value 不必使用 Object 类型。还消除了 Field.exec(...) 中的 null 值判断
     */
    public static class NullFieldGetter extends FieldGetter {

        public static final NullFieldGetter me = new NullFieldGetter();

        public boolean notNull() {
            return false;
        }

        public FieldGetter takeOver(Class<?> targetClass, String fieldName) {
            throw new RuntimeException("The method takeOver(Class, String) of NullFieldGetter should not be invoked");
        }

        public Object get(Object target, String fieldName) throws Exception {
            throw new RuntimeException("The method get(Object, String) of NullFieldGetter should not be invoked");
        }
    }

    /**
     * GetterMethodFieldGetter
     *
     * 使用 getter 方法获取 target.field 表达式的值
     */
    public static class GetterMethodFieldGetter extends FieldGetter {

        protected java.lang.reflect.Method getterMethod;

        public GetterMethodFieldGetter(java.lang.reflect.Method getterMethod) {
            this.getterMethod = getterMethod;
        }

        public FieldGetter takeOver(Class<?> targetClass, String fieldName) {
            if (MethodKit.isForbiddenClass(targetClass)) {
                throw new RuntimeException("Forbidden class: " + targetClass.getName());
            }

            String getterName = "get" + StrKit.firstCharToUpperCase(fieldName);
            java.lang.reflect.Method[] methodArray = targetClass.getMethods();
            for (java.lang.reflect.Method method : methodArray) {
                if (method.getName().equals(getterName) && method.getParameterCount() == 0) {
                    // if (MethodKit.isForbiddenMethod(getterName)) {
                        // throw new RuntimeException("Forbidden method: " + getterName);
                    // }

                    return new GetterMethodFieldGetter(method);
                }
            }

            return null;
        }

        public Object get(Object target, String fieldName) throws Exception {
            return getterMethod.invoke(target, ExprList.NULL_OBJECT_ARRAY);
        }

        public String toString() {
            return getterMethod.toString();
        }
    }

    /**
     * IsMethodFieldGetter
     *
     * 使用 target.isXxx() 方法获取值，默认不启用该功能，用户可以通过如下方式启用：
     * Engine.addLastFieldGetter(new FieldGetters.IsMethodFieldGetter());
     */
    public static class IsMethodFieldGetter extends FieldGetter {

        protected java.lang.reflect.Method isMethod;

        // 此构造方法仅为了方便在 Engine.addFieldGetter(...) 添加时不用为构造方法传参
        public IsMethodFieldGetter() {
        }

        public IsMethodFieldGetter(java.lang.reflect.Method isMethod) {
            this.isMethod = isMethod;
        }

        public FieldGetter takeOver(Class<?> targetClass, String fieldName) {
            if (MethodKit.isForbiddenClass(targetClass)) {
                throw new RuntimeException("Forbidden class: " + targetClass.getName());
            }

            String isMethodName = "is" + StrKit.firstCharToUpperCase(fieldName);
            java.lang.reflect.Method[] methodArray = targetClass.getMethods();
            for (java.lang.reflect.Method method : methodArray) {
                if (method.getName().equals(isMethodName) && method.getParameterCount() == 0) {
                    Class<?> returnType = method.getReturnType();
                    if (returnType == Boolean.class || returnType == boolean.class) {
                        return new IsMethodFieldGetter(method);
                    }
                }
            }

            return null;
        }

        public Object get(Object target, String fieldName) throws Exception {
            return isMethod.invoke(target, ExprList.NULL_OBJECT_ARRAY);
        }

        public String toString() {
            return isMethod.toString();
        }
    }

    /**
     * ModelFieldGetter
     *
     * 使用 Model.get(String) 获取值
     */
    public static class ModelFieldGetter extends FieldGetter {

        // 所有 Model 可以共享 ModelFieldGetter 获取属性
        static final ModelFieldGetter singleton = new ModelFieldGetter();

        public FieldGetter takeOver(Class<?> targetClass, String fieldName) {
            if (com.jfinal.plugin.activerecord.Model.class.isAssignableFrom(targetClass)) {
                return singleton;
            } else {
                return null;
            }
        }

        public Object get(Object target, String fieldName) throws Exception {
            return ((com.jfinal.plugin.activerecord.Model<?>)target).get(fieldName);
        }
    }

    /**
     * RecordFieldGetter
     *
     * 使用 Record.get(String) 获取值
     */
    public static class RecordFieldGetter extends FieldGetter {

        // 所有 Record 可以共享 RecordFieldGetter 获取属性
        static final RecordFieldGetter singleton = new RecordFieldGetter();

        public FieldGetter takeOver(Class<?> targetClass, String fieldName) {
            if (com.jfinal.plugin.activerecord.Record.class.isAssignableFrom(targetClass)) {
                return singleton;
            } else {
                return null;
            }
        }

        public Object get(Object target, String fieldName) throws Exception {
            return ((com.jfinal.plugin.activerecord.Record)target).get(fieldName);
        }
    }

    /**
     * MapFieldGetter
     *
     * 使用 Map.get(Object) 获取值
     */
    public static class MapFieldGetter extends FieldGetter {

        // 所有 Map 可以共享 MapFieldGetter 获取属性
        static final MapFieldGetter singleton = new MapFieldGetter();

        public FieldGetter takeOver(Class<?> targetClass, String fieldName) {
            if (java.util.Map.class.isAssignableFrom(targetClass)) {
                return singleton;
            } else {
                return null;
            }
        }

        public Object get(Object target, String fieldName) throws Exception {
            return ((java.util.Map<?, ?>)target).get(fieldName);
        }
    }

    /**
     * RealFieldGetter
     *
     * 使用 target.field 获取值
     */
    public static class RealFieldGetter extends FieldGetter {

        protected java.lang.reflect.Field field;

        public RealFieldGetter(java.lang.reflect.Field field) {
            this.field = field;
        }

        public FieldGetter takeOver(Class<?> targetClass, String fieldName) {
            java.lang.reflect.Field[] fieldArray = targetClass.getFields();
            for (java.lang.reflect.Field field : fieldArray) {
                if (field.getName().equals(fieldName)) {
                    return new RealFieldGetter(field);
                }
            }

            return null;
        }

        public Object get(Object target, String fieldName) throws Exception {
            return field.get(target);
        }

        public String toString() {
            return field.toString();
        }
    }

    /**
     * ArrayLengthGetter
     *
     * 获取数组长度： array.length
     */
    public static class ArrayLengthGetter extends FieldGetter {

        // 所有数组可以共享 ArrayLengthGetter 获取属性
        static final ArrayLengthGetter singleton = new ArrayLengthGetter();

        public FieldGetter takeOver(Class<?> targetClass, String fieldName) {
            if ("length".equals(fieldName) && targetClass.isArray()) {
                return singleton;
            } else {
                return null;
            }
        }

        public Object get(Object target, String fieldName) throws Exception {
            return Array.getLength(target);
        }
    }
}








